KR20070052897A - Electron emission display device - Google Patents

Abstract

The present invention relates to an electron emission display device capable of suppressing electron beam distortion around a spacer due to a temperature difference between a first substrate and a second substrate. The electron emission display device according to the present invention includes a first substrate and a second substrate disposed to face each other, electron emission portions formed on the first substrate, and a driving electrode provided on the first substrate to control electron emission of the electron emission portions. And the fluorescent layers and the black layer formed adjacent to each other on one surface of the second substrate, the anode electrode formed on one surface of the fluorescent layers and the black layer, and spacers positioned between the first substrate and the second substrate. And the first substrate and the second substrate satisfy the following conditions in the driving process.

0.9 ≤ T2 / T1 ≤ 1

Here, T1 (° C) represents the temperature of the first substrate, and T2 (° C) represents the temperature of the second substrate.

First substrate, second substrate, spacer, temperature, fluorescent layer, black layer, driving electrode

Description

Electron Emission Display Device {ELECTRON EMISSION DISPLAY DEVICE}

1 is a partially exploded perspective view of an electron emission display device according to an exemplary embodiment of the present invention.

2 is a graph showing the degree of electron beam distortion around a spacer according to a change in the temperature ratio of the first substrate and the second substrate.

TECHNICAL FIELD The present invention relates to an electron emission display device, and more particularly, to an electron emission display device capable of suppressing electron beam distortion around a spacer due to a temperature difference between a first substrate and a second substrate.

In general, an electron emission element may be classified into a method using a hot cathode and a method using a cold cathode according to the type of electron source.

Here, the electron-emitting device using the cold cathode is a field emitter array (FEA) type, a surface conduction emission type (SCE) type, a metal-insulation layer-metal Metal (MIM) type and Metal-Insulator-Semiconductor (MIS) type are known.

The field emission array (FEA) type electron emission device includes an electron emission portion and a driving electrode for controlling electron emission of the electron emission portion, and includes one cathode electrode and one gate electrode. The use of low or high aspect ratio materials, such as carbon nanotubes and carbon-based materials such as graphite and diamond-like carbon, utilizes the principle that electrons are easily released by an electric field in vacuum.

The electron emission devices are arranged in an array on the first substrate to form an electron emission device, and the electron emission device is combined with a second substrate having a light emitting unit composed of a fluorescent layer and an anode electrode to emit electrons. A display device (electron emission display device) is constituted.

The edges of the first substrate and the second substrate are integrally bonded by the sealing member, and then the inside thereof is exhausted to form a vacuum container. In addition, a plurality of spacers are disposed inside the vacuum container to maintain a constant distance between the first substrate and the second substrate, and to support the compressive force applied to the vacuum container to prevent deformation and breakage of the vacuum container.

In the above-described electron emission display device, the driving electrodes provided on the first substrate and the anode electrode provided on the second substrate generate heat during driving, and in particular, a large amount of heat is generated on the driving electrodes on the side of the first substrate emitting electrons. As a result, the first substrate and the second substrate maintain different temperatures.

At this time, since the inside of the vacuum vessel is maintained at a vacuum degree of approximately 10 ⁻⁶ torr, heat transfer through convection is blocked, but thermal conduction occurs through spacers disposed between the first substrate and the second substrate. The temperature difference along the height direction of the spacer causes a change in the potential of the spacer surface along this height direction, thereby distorting the equipotential lines around the spacer. In general, the portion where the spacer is disposed shows an equipotential line distribution that is higher toward the second substrate than the other portion.

As a result, the electrons emitted from the electron emission unit around the spacer do not go straight to the corresponding fluorescent layer but proceed toward the fluorescent layer of the black layer or the neighboring unit pixel. In particular, when the other color fluorescent layer of the neighboring unit pixel emits light, there is a problem that the display quality is degraded, such as the color purity of the screen is lowered.

Accordingly, an object of the present invention is to provide an electron emission display device capable of suppressing electron beam distortion around a spacer through an optimized temperature setting of a first substrate and a second substrate. .

In order to achieve the above object, the present invention,

A first substrate and a second substrate disposed to face each other, electron emission portions formed on the first substrate, driving electrodes provided on the first substrate to control electron emission of the electron emission portions, and a surface of the second substrate. A fluorescent layer and a black layer formed adjacent to each other, an anode electrode formed on one surface of the fluorescent layers and the black layer, and spacers positioned between the first substrate and the second substrate, the first substrate and the second substrate An electron emission display device in which a substrate satisfies the following conditions in a driving process is provided.

0.9 ≤ T2 / T1 ≤ 1

Here, T1 (° C) represents the temperature of the first substrate, and T2 (° C) represents the temperature of the second substrate.

The driving electrodes may include cathode electrodes electrically connected to the electron emission parts, and gate electrodes positioned to be insulated from the cathode electrodes, and further include a focusing electrode positioned to be insulated from the driving electrodes on the driving electrodes. It may include.

The electron emission unit may include at least one material selected from the group consisting of carbon nanotubes, graphite, graphite nanofibers, diamonds, diamond-like carbons, C _60, and silicon nanowires.

The black layer may be formed to have a width of approximately 80 μm between the fluorescent layers. The spacers are made of a dielectric and may be located corresponding to the black layer.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a partially exploded perspective view of an electron emission display device according to an exemplary embodiment of the present invention. As an example, a field emission array (FEA) type electron emission display device is illustrated.

Referring to the drawings, the electron emission display device includes a first substrate 2 and a second substrate 4 which are disposed to be parallel to each other at predetermined intervals. Sealing members (not shown) are disposed at the edges of the first substrate 2 and the second substrate 4 to bond the two substrates, and the internal space is evacuated with a vacuum of approximately 10 ⁻⁶ torr to allow the first substrate 2 to be bonded. ), The second substrate 4 and the sealing member constitute a vacuum container.

On the opposite surface of the first substrate 2 to the second substrate 4, electron emission elements are arranged in an array to form the electron emission device 100, and the electron emission device 100 is connected to the second substrate 4. ) And the light emitting unit 110 provided on the second substrate 4 to form an electron emission display device.

First, the cathode electrodes 6, which are first electrodes, are formed in a stripe pattern along one direction (y-axis direction in the drawing) of the first substrate 2, and the cathode electrodes 6 are formed on the first substrate 2. The first insulating layer 8 is formed on the entire first substrate 2 while covering it. Gate electrodes 10, which are second electrodes, are formed on the first insulating layer 8 in a stripe pattern along a direction orthogonal to the cathode electrode 6 (x-axis direction in the drawing).

In the above, an intersection area between the cathode electrode 6 and the gate electrode 10 forms one unit pixel, and one or more electron emission units 12 are formed on each unit pixel above the cathode electrodes 6. Openings 81 and 101 corresponding to the electron emission portions 12 are formed in the first insulating layer 8 and the gate electrode 10 to expose the electron emission portions 12 on the first substrate 2. .

The electron emission unit 12 may be made of materials emitting electrons, for example, carbon-based materials or nanometer-sized materials, when an electric field is applied in a vacuum. The electron emission unit 12 may include, for example, carbon nanotubes, graphite, graphite nanofibers, diamonds, diamond-like carbons, C _60, silicon nanowires _, and combinations thereof. Screen printing, direct growth, chemical vapor deposition or sputtering may be applied.

In the drawing, the electron emission parts 12 are formed in a circular shape and arranged in a line along the length direction of the cathode electrode 6 in each unit pixel. However, the planar shape of the electron emission unit 12, the number and arrangement form per unit pixel, and the like are not limited to the illustrated example and may be variously modified.

In addition, the structure in which the gate electrodes 10 are positioned on the cathode electrodes 6 with the first insulating layer 8 therebetween has been described. However, the gate electrodes 10 have the first insulating layer therebetween. A structure located below the field is also possible. In this case, the electron emission part may be positioned on the side of the cathode electrode on the first insulating layer.

The focusing electrode 14, which is a third electrode, is formed on the gate electrodes 10 and the first insulating layer 8. A second insulating layer 16 is positioned below the focusing electrode 14 to insulate the gate electrode 10 and the focusing electrode 14, and to pass the electron beam through the second insulating layer 16 and the focusing electrode 14. Openings 161 and 141 are provided.

The focusing electrode 14 forms one opening corresponding to each of the electron emission units 12 to individually collect electrons emitted from each electron emission unit 12, or one opening per unit pixel to form one opening. The electrons emitted from the unit pixel may be collectively focused. 1 shows the second case.

Next, on one surface of the second substrate 4 facing the first substrate 2, the fluorescent layer 18, for example, the red, green, and blue fluorescent layers 18R, 18G, and 18B may be disposed at random intervals. The black layer 20 is formed between the fluorescent layers 18 to improve contrast of the screen. The fluorescent layer 18 is formed so that the fluorescent layers 18R, 18G, and 18B of one color correspond to the unit pixels set on the first substrate 2.

An anode electrode 22 made of a metal film such as aluminum is formed on the fluorescent layer 18 and the black layer 20. The anode 22 receives a high voltage necessary for accelerating the electron beam from the outside, and reflects the visible light emitted toward the first substrate 2 of the visible light emitted from the fluorescent layer 18 toward the second substrate 4 to improve luminance. Height plays a role.

On the other hand, the anode electrode may be made of a transparent conductive film such as indium tin oxide (ITO) rather than a metal film. In this case, the anode electrode is positioned on one surface of the fluorescent layer 18 and the black layer 20 facing the second substrate 4, and may be formed in plural in a predetermined pattern. In addition, a structure in which the above-described transparent conductive film and the metal film are formed simultaneously on both surfaces of the fluorescent layer 18 and the black layer 20 as an anode electrode is also possible.

Spacers 24 are disposed between the first substrate 2 and the second substrate 4 to support the compressive force applied to the vacuum container, and to maintain a constant gap between the two substrates 2 and 4. The spacers 24 are made of a dielectric such as glass, ceramic, or tempered glass to prevent short-circuit between the focusing electrode 14 and the anode electrode 22, and the black layer (not to invade the fluorescent layer 18). 20). In the drawings, a wall-type spacer 24 is shown as an example.

The electron emission display device having the above configuration is driven by supplying a predetermined voltage to the cathode electrodes 6, the gate electrodes 10, the focusing electrode 14, and the anode electrode 22 from the outside.

For example, any one of the cathode electrodes 6 and the gate electrodes 10 receives a scan driving voltage to function as a scan electrode, and the other electrodes receive a data driving voltage to function as a data electrode. In addition, the focusing electrode 14 receives a voltage required for electron beam focusing, for example, 0 V or a negative DC voltage of several to several tens of volts, and the anode electrode 22 requires a voltage for accelerating the electron beam, for example, several hundred to several thousand volts. DC voltage of is applied.

As a result, an electric field is formed around the electron emission unit 12 in the unit pixels in which the voltage difference between the cathode electrode 6 and the gate electrode 10 is greater than or equal to a threshold, and electrons are emitted therefrom. The emitted electrons are focused to the center of the electron beam bundle while passing through the focusing electrode opening 141, and are attracted by the high voltage applied to the anode electrode 22 to collide with the corresponding fluorescent layer 18 to emit light.

In the above driving process of the electron emission display device, the driving electrodes on the side of the first substrate 2 from which the electrons are emitted, that is, the cathode electrode 6 and the gate electrode 10, and the second substrate 4 for accelerating the electrons 4. Heat is emitted from the anode electrode 22 on the side of), and in particular, a greater amount of heat is emitted from the drive electrodes on the side of the first substrate 2 on which the electron emission portion 12 is located. As a result, the first substrate 2 and the second substrate 4 maintain different temperatures, and the temperature difference leads to the change of the equipotential line around the spacer 24 and the electron beam distortion.

Therefore, the electron emission display device according to the present embodiment satisfies the following conditions in order to minimize electron beam distortion.

0.9 ≤ T2 / T1 ≤ 1

Here, T1 (° C) represents the temperature of the first substrate, and T2 (° C) represents the temperature of the second substrate.

2 is a graph showing the degree of electron beam distortion around the spacer according to the change in the temperature ratio of the first substrate 2 and the second substrate 4. The horizontal axis of the graph represents T2 / T1, and the vertical axis represents the moving distance of the electron beam (mu m) due to the electric field change around the spacer 24.

In the electron emission display device used in the experiment, the fluorescent layer 18 is formed to have a width of approximately 340 μm, and the black layer 20 has a width of approximately 80 μm and the fluorescent layer 18 is disposed between the respective fluorescent layers 18. ) So that it surrounds The width of the fluorescent layer 18 and the black layer 20 is a direction in which the fluorescent layers 18R, 18G, and 18B of different colors are disposed adjacent to each other (the x-axis direction in the drawing), that is, the horizontal direction of the screen. It can be defined as the width measured accordingly.

The moving distance of the electron beam is an electron beam distorted along the width direction (x-axis direction in the drawing) of the fluorescent layer 18 on the basis of the electron beam spot position when the electron beam goes straight toward the fluorescent layer 18 of the corresponding unit pixel. It can be defined as the distance to the spot position.

Referring to FIG. 2, when the temperature ratio (T2 / T1) of the first substrate and the second substrate satisfies the modification condition of the present embodiment, it can be seen that the electron beam moving distance is 80 μm or less, and the result shows that the electron beam has a black layer. This means that the electron beam spot is formed in the area (20) so that no other color emission occurs.

As described above, the electron emission display device of the present embodiment suppresses electron beam distortion around the spacer 24 by optimizing temperature settings of the first substrate and the second substrate, thereby suppressing the light emission of the fluorescent layer 18. It has the effect of improving the display purity by improving the color purity.

In the above, the field emission array (FEA) type electron emission display device has been described. Applicable

In addition, although the preferred embodiment of the present invention has been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it is within the scope of the present invention.

As described above, the electron emission display device according to the present invention suppresses electron beam distortion generated around the spacer when the electron emission display device is driven through temperature optimization of the first substrate and the second substrate. Accordingly, the electron emission display device according to the present invention suppresses the emission of other colors of the electron beam, thereby improving the color purity of the screen, thereby realizing the effect of improving the display quality.

Claims (6)

A first substrate and a second substrate disposed to face each other; Electron emission parts formed on the first substrate; Drive electrodes provided on the first substrate to control electron emission of the electron emission parts; Fluorescent layers and a black layer formed adjacent to each other on one surface of the second substrate; An anode formed on one surface of the fluorescent layers and the black layer; And Spacers positioned between the first substrate and the second substrate, An electron emission display device in which the first substrate and the second substrate satisfy the following conditions in a driving process. 0.9 ≤ T2 / T1 ≤ 1 Here, T1 (° C) represents the temperature of the first substrate, and T2 (° C) represents the temperature of the second substrate. The method of claim 1, And cathode electrodes in which the driving electrodes are electrically connected to the electron emission parts, and gate electrodes insulated from the cathode electrodes. The method of claim 2, And a focusing electrode positioned to be insulated from the driving electrodes on the driving electrodes. The method of claim 1, And at least one material selected from the group consisting of carbon nanotubes, graphite, graphite nanofibers, diamonds, diamond-like carbons, C ₆₀ and silicon nanowires. The method of claim 1, And the black layer is formed between the fluorescent layers with a width of approximately 80 μm. The method of claim 1, And the spacers are made of a dielectric and positioned to correspond to the black layer.

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